In the retail industry, flat bed laser readers, also known as horizontal slot scanners, have been used to electro-optically read one-dimensional bar code symbols, particularly of the Universal Product Code (UPC) type, at full-service, point-of-transaction checkout terminals operated by checkout clerks in supermarkets, warehouse clubs, department stores, and other kinds of retailers for many years. As exemplified by U.S. Pat. No. 5,059,779; No. 5,124,539 and No. 5,200,599, a single, horizontal window is set flush with, and built into, a horizontal countertop of the terminal. Products to be purchased bear identifying symbols and are typically slid across the horizontal window through which a multitude of scan lines is projected in a generally upwards direction. When at least one of the scan lines sweeps over a symbol associated with a product, the symbol is processed and read. The multitude of scan lines is typically generated by a scan pattern generator which includes a laser for emitting a laser beam at a mirrored component mounted on a shaft for rotation by a motor about an axis. A plurality of stationary mirrors is arranged about the axis. As the mirrored component turns, the laser beam is successively reflected onto the stationary mirrors for reflection therefrom through the horizontal window as a scan pattern of the scan lines.
It is also known to provide a checkout terminal not only with a generally horizontal window, but also with an upright or generally vertical window that faces the clerk at the terminal. The generally vertical window is oriented generally perpendicularly to the horizontal window, or is slightly rearwardly or forwardly inclined. The laser scan pattern generator within this dual window or bioptical terminal also projects the multitude of scan lines in a generally outward direction through the vertical window toward the clerk. The generator for the vertical window can be the same as or different from the generator for the horizontal window. The clerk slides the products past either window, e.g., from right to left, or from left to right, in a “swipe” mode. Alternatively, the clerk merely presents the symbol on the product to a central region of either window in a “presentation” mode. The choice depends on clerk preference or on the layout of the terminal.
Sometimes, the vertical window is not built into the terminal as a permanent installation. Instead, a vertical slot scanner is configured as a portable reader that is placed on the countertop of an existing horizontal slot scanner in a hands-free mode of operation. In the frequent event that large, heavy, or bulky products, that cannot easily be brought to the reader, have symbols that are required to be read, then the clerk may also manually grasp the portable reader and lift it off, and remove it from, the countertop for reading the symbols in a handheld mode of operation.
As advantageous as these laser-based, point-of-transaction terminals are in processing transactions involving products associated with one-dimensional symbols, each having a row of bars and spaces spaced apart along one direction, these terminals cannot process stacked symbols, such as Code 49 that introduced the concept of vertically stacking a plurality of rows of bar and space patterns in a single symbol, as described in U.S. Pat. No. 4,794,239, or two-dimensional symbols, such as PDF417 that increased the amount of data that could be represented or stored on a given amount of surface area, as described in U.S. Pat. No. 5,304,786. Both one- and two-dimensional symbols, as well as stacked symbols, can be read by employing imaging readers each having a solid-state imager which has a one- or two-dimensional array of cells or photosensors that correspond to image elements or pixels in a field of view of the imager. Such an imager may include a one- or two-dimensional charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device, as well as associated circuits for producing electronic signals corresponding to the one- or two-dimensional array of pixel information over the field of view.
It is therefore known to use a solid-state imager for capturing a monochrome image of a symbol as, for example, disclosed in U.S. Pat. No. 5,703,349. It is also known to use a solid-state imager with multiple buried channels for capturing a full color image of a target as, for example, disclosed in U.S. Pat. No. 4,613,895. It is common to provide a two-dimensional CCD with a 640×480 resolution commonly found in VGA monitors, although other resolution sizes are possible.
It is also known to install the solid-state imager, analogous to that conventionally used in a consumer digital camera, in a bioptical, point-of-transaction terminal, as disclosed in U.S. Pat. No. 7,191,947 in which the dual use of both the solid-state imager and the laser scan pattern generator in the same terminal is disclosed. It is possible to replace all of the laser scan pattern generators with solid-state imagers in order to improve reliability and to enable the reading of two-dimensional and stacked symbols, as well as other targets.
All of the above-described terminals are typically operated by checkout clerks. In an effort to reduce, if not eliminate, the need for checkout clerks and their associated labor cost, a number of self-service, point-of-sale, checkout terminals have been proposed. A self-service checkout terminal is operated by the customer without the aid of the checkout clerk. During operation of the self-service checkout terminal, the customer moves individual products for purchase across a window of the terminal to read their respective symbols, and then places the read products into a carry-out bag, if desired. The customer then pays for his or her purchases either at the self-service checkout terminal if so equipped with a credit/debit card reader, or at a central payment area that is staffed by a store employee. Thus, the self-service checkout terminal permits the customer to select, itemize, and, in some cases, pay for his or her purchases, without the assistance of the retailer's personnel.
However, the known self-service checkout terminals are relatively expensive to install and are sometimes difficult for some customers to operate, thereby potentially causing such terminals to go unused or underutilized, and their expense to be economically unjustified. Some retailers expect their clerks to stand nearby self-service terminals to be rapidly called in for assistance when necessary. Some self-service terminals require that certain equipment be moved into position depending on whether the customer or the clerk is handling the transaction. Dedicated self-service terminals occupy valuable real estate in a retailer's operation, which might otherwise be used for full-service terminals. Full-service terminals are not readily convertible into self-service terminals.